Image sensors and methods of operating the same

ABSTRACT

Disclosed herein is a method of using an image sensor comprising N sensing areas for capturing images of a scene, the N sensing areas being physically separate from each other, the method comprising: for i=1, . . . , P, and j=1, . . . , Q(i), positioning the image sensor at a location (i,j) and capturing a partial image (i,j) of the scene using the image sensor while the image sensor is at the location (i,j), thereby capturing in total R partial images, wherein R is the sum of Q(i), i=1, . . . , P, wherein P&gt;1, wherein Q(i), i=1, . . . , P are positive integers and are not all 1, wherein for i=1, . . . , P, a location group (i) comprises the locations (i,j), j=1, . . . , Q(i), and wherein a minimum distance between 2 locations of 2 different location groups is substantially larger than a maximum distance between two locations of a same location group; and determining a combined image of the scene based on the R partial images.

TECHNICAL FIELD

The disclosure herein relates to image sensors and methods of operatingthe same.

BACKGROUND

A radiation detector is a device that measures a property of aradiation. Examples of the property may include a spatial distributionof the intensity, phase, and polarization of the radiation. Theradiation may be one that has interacted with an object. For example,the radiation measured by the radiation detector may be a radiation thathas penetrated the object. The radiation may be an electromagneticradiation such as infrared light, visible light, ultraviolet light,X-ray or γ-ray. The radiation may be of other types such as α-rays andβ-rays. An image sensor may include multiple radiation detectors. Theradiation may include radiation particles such as photons (i.e.,electromagnetic waves) and subatomic particles.

SUMMARY

Disclosed herein is a method of using an image sensor comprising Nsensing areas for capturing images of a scene, N being a positiveinteger, the N sensing areas being physically separate from each other,the method comprising: for i=1, . . . , P, and j=1, . . . , Q(i),positioning the image sensor at a location (i,j) relative to the sceneand capturing a partial image (i,j) of the scene using the image sensorwhile the image sensor is at the location (i,j), thereby capturing intotal R partial images, wherein R is the sum of Q(i), i=1, . . . , P,wherein P is an integer greater than 1, wherein Q(i), i=1, . . . , P arepositive integers and are not all 1, wherein for i=1, . . . , P, alocation group (i) comprises the locations (i,j), j=1, . . . , Q(i), andwherein a minimum distance between a location of a location group of thelocation groups (i), i=1, . . . , P and another location of anotherlocation group of the location groups (i), i=1, . . . , P issubstantially larger than a maximum distance between two locations of alocation group of the location groups (i), i=1, . . . , P; anddetermining a combined image of the scene based on the R partial images.

According to an embodiment, N is greater than 1.

According to an embodiment, said positioning the image sensor at thelocations (i,j) for i=1, . . . , P, and j=1, . . . , Q(i) are performedone by one.

According to an embodiment, Q(i), i=1, . . . , P are the same andgreater than 1.

According to an embodiment, said minimum distance is close to and lessthan a size of a sensing area of the N sensing areas.

According to an embodiment, said minimum distance is more than 100 timessaid maximum distance.

According to an embodiment, said maximum distance is less than 10 timesa size of a sensing element of the N sensing areas.

According to an embodiment, said positioning the image sensor at thelocations (i,j) for i=1, . . . , P, and j=1, . . . , Q(i) comprisesmoving the image sensor from a location of a location group of thelocation groups (i), i=1, . . . , P directly to another location ofanother location group of the location groups (i), i=1, . . . , P anddoes not comprise moving the image sensor from a location of a locationgroup of the location groups (i), i=1, . . . , P directly to anotherlocation of the same location group.

According to an embodiment, said determining the combined imagecomprises stitching the partial images (i,1), i=1, . . . , P to form astitched image of the scene.

According to an embodiment, said determining the combined image furthercomprises for i=1, . . . , P determining an enhanced partial image (i)based on the partial images (i,j), j=1, . . . , Q(i).

According to an embodiment, said determining the combined image furthercomprises for i=1, . . . , P using the enhanced partial image (i) toreplace the partial image (i,1) of the stitched image.

According to an embodiment, said determining the combined image furthercomprises equalizing resolutions of different regions of the stitchedimage after said using is performed.

According to an embodiment, said determining the combined image furthercomprises for i=1, . . . , P using the enhanced partial image (i) toreplace the partial image (i,1) of the stitched image if a resolution ofthe enhanced partial image (i) is higher than that of the partial image(i,1).

According to an embodiment, said determining the enhanced partial images(i) comprises determining positions of the locations (i,j), j=1, . . . ,Q(i) relative to each other.

According to an embodiment, said determining the positions of thelocations (i,j), j=1, . . . , Q(i) relative to each other comprisesusing markers which are stationary relative to the scene.

According to an embodiment, said determining the positions of thelocations (i,j), j=1, . . . , Q(i) relative to each other comprises:upsampling the partial images (i,j), j=1, . . . , Q(i) resulting inupsampled partial images (i,j), j=1, . . . , Q(i) respectively; andcorrelating the upsampled partial images (i,j), j=1, . . . , Q(i) todetermine the positions of the locations (i,j), j=1, . . . , Q(i)relative to each other.

According to an embodiment, said determining the combined imagecomprises for i=1, . . . , P determining an enhanced partial image (i)based on the partial images (i,j), j=1, . . . , Q(i).

According to an embodiment, said determining the combined image furthercomprises stitching the enhanced partial images (i), i=1, . . . , P toform a stitched image of the scene.

According to an embodiment, said determining the combined image furthercomprises equalizing resolutions of different regions of the stitchedimage.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 schematically shows a radiation detector, according to anembodiment.

FIG. 2A schematically shows a simplified cross-sectional view of theradiation detector.

FIG. 2B schematically shows a detailed cross-sectional view of theradiation detector.

FIG. 2C schematically shows an alternative detailed cross-sectional viewof the radiation detector.

FIG. 3 schematically shows a top view of a package including theradiation detector and a printed circuit board (PCB).

FIG. 4 schematically shows a cross-sectional view of an image sensor,where a plurality of the packages of FIG. 3 are mounted to a system PCB,according to an embodiment.

FIG. 5A-FIG. 5D schematically show top views of the image sensor inoperation, according to an embodiment.

FIG. 6A-FIG. 6D schematically show top views of the image sensor inoperation, according to an alternative embodiment.

FIG. 7 shows a flowchart summarizing the operation of the image sensor,according to an embodiment.

FIG. 8 shows another flowchart summarizing and generalizing an operationof the image sensor, according to an embodiment.

DETAILED DESCRIPTION

FIG. 1 schematically shows a radiation detector 100, as an example. Theradiation detector 100 may include an array of sensing elements 150(also referred to as pixels 150). The array may be a rectangular array(as shown in FIG. 1), a honeycomb array, a hexagonal array or any othersuitable array. The radiation detector 100 in the example of FIG. 1 has28 sensing elements 150 arranged in 7 rows and 4 columns; however, ingeneral, the radiation detector 100 may have any number of sensingelements 150 arranged in any way.

Each sensing element 150 may be configured to detect radiation from aradiation source (not shown) incident thereon and may be configured tomeasure a characteristic (e.g., the energy of the particles, thewavelength, and the frequency) of the radiation. A radiation may includeparticles such as photons (electromagnetic waves) and subatomicparticles. Each sensing element 150 may be configured to count numbersof particles of radiation incident thereon whose energy falls in aplurality of bins of energy, within a period of time. All the sensingelements 150 may be configured to count the numbers of particles ofradiation incident thereon within a plurality of bins of energy withinthe same period of time. When the incident particles of radiation havesimilar energy, the sensing elements 150 may be simply configured tocount numbers of particles of radiation incident thereon within a periodof time, without measuring the energy of the individual particles ofradiation.

Each sensing element 150 may have its own analog-to-digital converter(ADC) configured to digitize an analog signal representing the energy ofan incident particle of radiation into a digital signal, or to digitizean analog signal representing the total energy of a plurality ofincident particles of radiation into a digital signal. The sensingelements 150 may be configured to operate in parallel. For example, whenone sensing element 150 measures an incident particle of radiation,another sensing element 150 may be waiting for a particle of radiationto arrive. The sensing elements 150 may not have to be individuallyaddressable.

The radiation detector 100 described here may have applications such asin an X-ray telescope, X-ray mammography, industrial X-ray defectdetection, X-ray microscopy or microradiography, X-ray castinginspection, X-ray non-destructive testing, X-ray weld inspection, X-raydigital subtraction angiography, etc. It may be suitable to use thisradiation detector 100 in place of a photographic plate, a photographicfilm, a PSP plate, an X-ray image intensifier, a scintillator, oranother semiconductor X-ray detector.

FIG. 2A schematically shows a simplified cross-sectional view of theradiation detector 100 of FIG. 1 along a line 2A-2A, according to anembodiment. More specifically, the radiation detector 100 may include aradiation absorption layer 110 and an electronics layer 120 (e.g., anASIC) for processing or analyzing electrical signals which incidentradiation generates in the radiation absorption layer 110. The radiationdetector 100 may or may not include a scintillator (not shown). Theradiation absorption layer 110 may comprise a semiconductor materialsuch as, silicon, germanium, GaAs, CdTe, CdZnTe, or a combinationthereof. The semiconductor material may have a high mass attenuationcoefficient for the radiation of interest.

FIG. 2B schematically shows a detailed cross-sectional view of theradiation detector 100 of FIG. 1 along the line 2A-2A, as an example.More specifically, the radiation absorption layer 110 may include one ormore diodes (e.g., p-i-n or p-n) formed by a first doped region 111, oneor more discrete regions 114 of a second doped region 113. The seconddoped region 113 may be separated from the first doped region 111 by anoptional intrinsic region 112. The discrete regions 114 are separatedfrom one another by the first doped region 111 or the intrinsic region112. The first doped region 111 and the second doped region 113 haveopposite types of doping (e.g., region 111 is p-type and region 113 isn-type, or region 111 is n-type and region 113 is p-type). In theexample of FIG. 2B, each of the discrete regions 114 of the second dopedregion 113 forms a diode with the first doped region 111 and theoptional intrinsic region 112. Namely, in the example in FIG. 2B, theradiation absorption layer 110 has a plurality of diodes (morespecifically, 7 diodes corresponding to 7 sensing elements 150 of onerow in the array of FIG. 1). The plurality of diodes have an electrode119A as a shared (common) electrode. The first doped region 111 may alsohave discrete portions.

The electronics layer 120 may include an electronic system 121 suitablefor processing or interpreting signals generated by the radiationincident on the radiation absorption layer 110. The electronic system121 may include an analog circuitry such as a filter network,amplifiers, integrators, and comparators, or a digital circuitry such asa microprocessor, and memory. The electronic system 121 may include oneor more ADCs. The electronic system 121 may include components shared bythe sensing elements 150 or components dedicated to a single sensingelement 150. For example, the electronic system 121 may include anamplifier dedicated to each sensing element 150 and a microprocessorshared among all the sensing elements 150. The electronic system 121 maybe electrically connected to the sensing elements 150 by vias 131. Spaceamong the vias may be filled with a filler material 130, which mayincrease the mechanical stability of the connection of the electronicslayer 120 to the radiation absorption layer 110. Other bondingtechniques are possible to connect the electronic system 121 to thesensing elements 150 without using the vias 131.

When radiation from the radiation source (not shown) hits the radiationabsorption layer 110 including diodes, particles of the radiation may beabsorbed and generate one or more charge carriers (e.g., electrons,holes) by a number of mechanisms. The charge carriers may drift to theelectrodes of one of the diodes under an electric field. The field maybe an external electric field. The electrical contact 1198 may includediscrete portions each of which is in electrical contact with thediscrete regions 114. The term “electrical contact” may be usedinterchangeably with the word “electrode.” In an embodiment, the chargecarriers may drift in directions such that the charge carriers generatedby a single particle of the radiation are not substantially shared bytwo different discrete regions 114 (“not substantially shared” heremeans less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow to a different one of the discrete regions114 than the rest of the charge carriers). Charge carriers generated bya particle of the radiation incident around the footprint of one ofthese discrete regions 114 are not substantially shared with another ofthese discrete regions 114. A sensing element 150 associated with adiscrete region 114 may be an area around the discrete region 114 inwhich substantially all (more than 98%, more than 99.5%, more than99.9%, or more than 99.99% of) charge carriers generated by a particleof the radiation incident therein flow to the discrete region 114.Namely, less than 2%, less than 1%, less than 0.1%, or less than 0.01%of these charge carriers flow beyond the sensing element 150.

FIG. 2C schematically shows an alternative detailed cross-sectional viewof the radiation detector 100 of FIG. 1 along the line 2A-2A, accordingto an embodiment. More specifically, the radiation absorption layer 110may include a resistor of a semiconductor material such as, silicon,germanium, GaAs, CdTe, CdZnTe, or a combination thereof, but does notinclude a diode. The semiconductor material may have a high massattenuation coefficient for the radiation of interest. In an embodiment,the electronics layer 120 of FIG. 2C is similar to the electronics layer120 of FIG. 2B in terms of structure and function.

When the radiation hits the radiation absorption layer 110 including theresistor but not diodes, it may be absorbed and generate one or morecharge carriers by a number of mechanisms. A particle of the radiationmay generate 10 to 100,000 charge carriers. The charge carriers maydrift to the electrical contacts 119A and 119B under an electric field.The electric field may be an external electric field. The electricalcontact 119B includes discrete portions. In an embodiment, the chargecarriers may drift in directions such that the charge carriers generatedby a single particle of the radiation are not substantially shared bytwo different discrete portions of the electrical contact 119B (“notsubstantially shared” here means less than 2%, less than 0.5%, less than0.1%, or less than 0.01% of these charge carriers flow to a differentone of the discrete portions than the rest of the charge carriers).Charge carriers generated by a particle of the radiation incident aroundthe footprint of one of these discrete portions of the electricalcontact 119B are not substantially shared with another of these discreteportions of the electrical contact 119B. A sensing element 150associated with a discrete portion of the electrical contact 119B may bean area around the discrete portion in which substantially all (morethan 98%, more than 99.5%, more than 99.9% or more than 99.99% of)charge carriers generated by a particle of the radiation incidenttherein flow to the discrete portion of the electrical contact 119B.Namely, less than 2%, less than 0.5%, less than 0.1%, or less than 0.01%of these charge carriers flow beyond the sensing element associated withthe one discrete portion of the electrical contact 119B.

FIG. 3 schematically shows a top view of a package 200 including theradiation detector 100 and a printed circuit board (PCB) 400. The term“PCB” as used herein is not limited to a particular material. Forexample, a PCB may include a semiconductor. The radiation detector 100is mounted to the PCB 400. The wiring between the detector 100 and thePCB 400 is not shown for the sake of clarity. The PCB 400 may have oneor more radiation detectors 100. The PCB 400 may have an area 405 notcovered by the radiation detector 100 (e.g., for accommodating bondingwires 410). The radiation detector 100 may have a sensing area 190,which is where the sensing elements 150 (FIG. 1) are located. Theradiation detector 100 may have a perimeter zone 195 near the edges ofthe radiation detector 100. The perimeter zone 195 has no sensingelements and the radiation detector 100 does not detect particles ofradiation incident on the perimeter zone 195.

FIG. 4 schematically shows a cross-sectional view of an image sensor490, according to an embodiment. The image sensor 490 may include aplurality of the packages 200 of FIG. 3 mounted to a system PCB 450. Asan example, the image sensor 490 may include 2 packages 200 as shown inFIG. 4. The electrical connection between the PCBs 400 and the systemPCB 450 may be made by bonding wires 410. In order to accommodate thebonding wires 410 on the PCB 400, the PCB 400 has the area 405 notcovered by the detector 100. In order to accommodate the bonding wires410 on the system PCB 450, the packages 200 have gaps in between. Thegaps may be approximately 1 mm or more. Particles of radiation incidenton the perimeter zones 195, on the area 405 or on the gaps cannot bedetected by the packages 200 on the system PCB 450.

A dead zone of a radiation detector (e.g., the radiation detector 100)is the area of the radiation-receiving surface of the radiationdetector, in which incident particles of radiation cannot be detected bythe radiation detector. A dead zone of a package (e.g., package 200) isthe area of the radiation-receiving surface of the package, in whichincident particles of radiation cannot be detected by the detector ordetectors in the package. In this example shown in FIG. 3 and FIG. 4,the dead zone of the package 200 includes the perimeter zones 195 andthe area 405. A dead zone (e.g., 488) of an image sensor (e.g., imagesensor 490) with a group of packages (e.g., packages mounted on the samePCB, packages arranged in the same layer) includes the combination ofthe dead zones of the packages in the group and the gaps among thepackages.

In an embodiment, the image sensor 490 including the radiation detectors100 may have the dead zone 488 incapable of detecting incidentradiation. However, in an embodiment, the image sensor 490 with sensingareas 190 may capture partial images of an object or scene (not shown),and then these captured partial images may be stitched to form a fullimage of the object or scene.

FIG. 5A-FIG. 5D schematically show top views of the image sensor 490 inoperation, according to an embodiment. For simplicity, only the 2sensing areas 190 a and 190 b and the dead zone 488 of the image sensor490 are shown (i.e., other parts of the image sensor 490 such asperimeter zones 195 (FIG. 4) are not shown). In an embodiment, acardboard box 510 enclosing a metal sword 512 may be positioned betweenthe image sensor 490 and a radiation source (not shown) which is beforethe page. The cardboard box 510 is between the image sensor 490 and theeye of viewer. Hereafter, for generalization, the cardboard box 510enclosing the metal sword 512 may be referred to as the object/scene510+512.

In an embodiment, the operation of the image sensor 490 in capturingimages of the object/scene 510+512 may be as follows. Firstly, theobject/scene 510+512 may be stationary, and the image sensor 490 may bemoved to a first image capture location relative to the object/scene510+512 as shown in FIG. 5A. Then, the image sensor 490 may be used tocapture a first partial image 520.1 of the object/scene 510+512 whilethe image sensor 490 is at the first image capture location.

Next, in an embodiment, the image sensor 490 may be moved to a secondimage capture location relative to the object/scene 510+512 as shown inFIG. 5B. Then, the image sensor 490 may be used to capture a secondpartial image 520.2 of the object/scene 510+512 while the image sensor490 is at the second image capture location.

Next, in an embodiment, the image sensor 490 may be moved to a thirdimage capture location relative to the object/scene 510+512 as shown inFIG. 5C. Then, the image sensor 490 may be used to capture a thirdpartial image 520.3 of the object/scene 510+512 while the image sensor490 is at the third image capture location.

In an embodiment, the size and shape of the sensing areas 190 a and 190b and the positions of the first, second, and third image capturelocations may be such that any partial image of the partial images520.1, 520.2, and 520.3 overlaps at least another partial image of thepartial images 520.1, 520.2, and 520.3. For example, a distance 492between the first and second image capture locations may be close to andless than a width 190 w of the sensing area 190 a; as a result, thefirst partial image 520.1 overlaps the second partial image 520.2.

In an embodiment, with any partial image of the partial images 520.1,520.2, and 520.3 overlapping at least another partial image of thepartial images 520.1, 520.2, and 520.3, the partial images 520.1, 520.2,and 520.3 may be stitched to form a more complete image 520 (FIG. 5D) ofthe object/scene 510+512. In an embodiment, the size and shape of thesensing areas 190 a and 190 b and the positions of the first, second,and third image capture locations may be such that the stitched image520 covers the entire object/scene 510+512 as shown in FIG. 5D.

FIG. 6A-FIG. 6D schematically show top views of the image sensor 490 inoperation, according to an alternative embodiment. In an embodiment, theoperation of the image sensor 490 in FIG. 6A-FIG. 6D may be similar tothe operation of the image sensor 490 in FIG. 5A-FIG. 5D with respect tothe capturing of the partial images 520.1, 520.2, and 520.3. In anembodiment, in addition to the capturing of the partial images 520.1,520.2, and 520.3 as described above, the operation of the image sensor490 in FIG. 6A-FIG. 6D may further include the following.

In an embodiment, after capturing the third partial image 520.3, theimage sensor 490 may be moved to a fourth image capture location (dashedrectangle 490 in FIG. 6A) at or near the first image capture location(solid rectangle 490 in FIG. 6A). Then, the image sensor 490 may be usedto capture a fourth partial image 520.4 of the object/scene 510+512while the image sensor 490 is at the fourth image capture location. Thefirst and fourth image capture locations may be considered to belong toa first location group. The first and fourth partial images may beconsidered to belong to a first partial image group.

In an embodiment, after capturing the fourth partial image 520.4, theimage sensor 490 may be moved to a fifth image capture location (dashedrectangle 490 in FIG. 6B) at or near the second image capture location(solid rectangle 490 in FIG. 6B). Then, the image sensor 490 may be usedto capture a fifth partial image 520.5 of the object/scene 510+512 whilethe image sensor 490 is at the fifth image capture location. The secondand fifth image capture locations may be considered to belong to asecond location group. The second and fifth partial images may beconsidered to belong to a second partial image group.

In an embodiment, after capturing the fifth partial image 520.5, theimage sensor 490 may be moved to a sixth image capture location (dashedrectangle 490 in FIG. 6C) at or near the third image capture location(solid rectangle 490 in FIG. 6C). Then, the image sensor 490 may be usedto capture a sixth partial image 520.6 of the object/scene 510+512 whilethe image sensor 490 is at the sixth image capture location. The thirdand sixth image capture locations may be considered to belong to a thirdlocation group. The third and sixth partial images may be considered tobelong to a third partial image group.

In an embodiment, the positions of the 6 image capture locations may besuch that the minimum distance between an image capture location of alocation group of the first, second, and third location groups andanother image capture location of another location group of the first,second, and third location groups is substantially larger than (e.g.,more than 10 times, more than 20 times, more than 50 times, or more than100 times) the maximum distance between 2 image capture locations of alocation group of the first, second, and third location groups. In otherwords, the minimum distance between 2 image capture locations of 2different location groups is substantially larger than the maximumdistance between 2 image capture locations of a same group.

In an embodiment, said minimum distance may be close to and less thanthe width 190 w (FIG. 5A) of the sensing area 190 a. For example, saidminimum distance may be in the range from 80% to 99.99% of the width 190w. In an embodiment, said minimum distance may be more than 100 timessaid maximum distance. In an embodiment, said maximum distance may beless than 10 times the size of a sensing element 150.

In an embodiment, the image sensor 490 may only move from an imagecapture location of a location group directly to another image capturelocation of another location group. This means that in this embodiment,the image sensor 490 may not move from an image capture location of alocation group directly to another image capture location of the samelocation group. For example, in this embodiment, the image sensor 490may move from the third image capture location directly to the fifthimage capture location because the third and fifth image capturelocations belong to two different location groups (i.e., the third andsecond location groups, respectively). However, in this embodiment, theimage sensor 490 may not move from the third image capture locationdirectly to the sixth image capture location because the third and sixthimage capture locations belong to the same location group (i.e., thethird location group).

Next, in an embodiment, after the 6 partial images 520.1-6 are captured,a combined image 620 (FIG. 6D) of the object/scene 510+512 may bedetermined based on the 6 partial images 520.1-6 as follows.Specifically, in an embodiment, the partial images 520.1, 520.2, and520.3 may be stitched to form a stitched image of the object/scene510+512.

Next, in an embodiment, a first enhanced partial image may be determinedfor the first partial image group based on the partial images 520.1 and520.4 of the first partial image group and then used to replace thepartial image 520.1 of the stitched image. In other words, the partialimage 520.4 is used to enhance the partial image 520.1 of the stitchedimage. More specifically, in an embodiment, the first enhanced partialimage may be determined as follows. Firstly, the positions of the firstand fourth image capture locations relative to each other may bedetermined by (A) measurement using markers or (B) estimation usinginter-image correlation.

In method (A), in an embodiment, markers may be added at fixed positionsrelative to the object/scene 510+512 such that at least one of themarkers is present in each of the partial images 520.1 and 520.4 of thefirst partial image group. For example, a marker 630 (FIG. 6A) is shownfor illustration (other markers are not shown for simplicity) and itsimages are in the partial images 520.1 and 520.4. In an embodiment, themarkers may have the shape of a cross (e.g., the marker 630). In anembodiment, the markers may comprise a metal such as aluminum. With thepositions of the markers relative to the object/scene 510+512 known, thepositions of the first and fourth image capture locations relative toeach other may be measured.

Method (B), in an embodiment, may involve correlating the 2 partialimages 520.1 and 520.4 to determine the positions of the first andfourth image capture locations relative to each other. Specifically, inan embodiment, two portions of the 2 partial images 520.1 and 520.4 ofthe first partial image group may be compared to determine a correlationcoefficient. In an embodiment, if the determined correlation coefficientexceeds a pre-specified threshold, the two portions from the 2 partialimages 520.1 and 520.4 may be considered identical and hence thepositions of the first and fourth image capture locations (correspondingto the partial images 520.1 and 520.4 respectively) relative to eachother may be estimated. In an embodiment, if the determined correlationcoefficient does not exceed the pre-specified threshold, the twoportions from the 2 partial images 520.1 and 520.4 may be considerednon-identical, and another two portions of the 2 partial images 520.1and 520.4 of the first partial image group may be compared, and so on.

In an embodiment, the resolutions of the 2 partial images 520.1 and520.4 of the first partial image group may be increased (upsampling)before the correlating process described above is performed. In anembodiment, this upsampling process may be performed usinginterpolation.

In an embodiment, with the positions of the first and fourth imagecapture locations relative to each other determined as described above,a resolution enhancing algorithm (also known as a super resolutionalgorithm) may be applied to the 2 partial images 520.1 and 520.4 of thefirst partial image group to form the first enhanced partial image. Inan embodiment, the first enhanced partial image may be used to replacethe first partial image 520.1 in the stitched image.

In an embodiment, in a similar manner, a second enhanced partial imagemay be determined for the second partial image group based on the 2partial images 520.2 and 520.5 of the group and then may be used toreplace the partial image 520.2 in the stitched image. Similarly, athird enhanced partial image may be determined for the third partialimage group based on the 2 partial images 520.3 and 520.6 of the groupand then may be used to replace the partial image 520.3 in the stitchedimage. In an embodiment, after the 3 replacements as described above, ifdifferent regions of the stitched image have different resolutions, thenalgorithms may be performed to cause the entire stitched image to havethe same resolution resulting in the combined image 620 (FIG. 6D).

FIG. 7 shows a flowchart 700 summarizing the operation of the imagesensor 490 according to FIG. 6A-FIG. 6D. Specifically, in step 710, theimage sensor 490 moves through different image capture locations andcaptures partial images while being at these image capture locations. Instep 720, some of the captured partial images (e.g., one partial imagefrom each partial image group) are stitched to form a stitched image ofthe scene. In step 730, for each partial image group, an enhancedpartial image is determined based on the partial images of the partialimage group, and the resulting enhanced partial image are used toreplace the corresponding partial image of the stitched image (i.e., toenhance the stitched image). In step 740, equalization of resolutions isperformed for the stitched image if necessary (i.e., if differentregions of the stitched image have different resolutions) resulting inthe combined image 620 of the object/scene 510+512 (FIG. 6D).

FIG. 8 shows a flowchart 800 summarizing and generalizing an operationof the image sensor 490, according to an embodiment. In step 810, theimage sensor 490 may be positioned at different locations, and differentpartial images of a same scene may be captured with the image sensor 490at these different locations, wherein a minimum distance between twolocations of two different location groups is substantially larger thana maximum distance between two locations of a location group. In anembodiment, the image sensor 490 may be positioned at these differentlocations one by one (i.e. at one location after another) for capturingthose partial images. In step 820, a combined image of the scene may bedetermined based on the captured partial images.

In the embodiments described above, with reference to FIG. 4, and FIG.5A-FIG. 5D, the image sensor 490 comprises 2 sensing areas 190 a and 190b which are physically separated from each other by the dead zone 488and in the shape of rectangles. In general, the image sensor 490 maycomprise N sensing areas 190 (N is a positive integer) which may bephysically separated from each other by a dead zone (e.g., dead zone488), may be in any size or shape, and may be arranged in any way.

In the embodiments described above, the cardboard box 510 enclosing themetal sword 512 is used as an example of the object or scene beingexamined. In general, any object or scene may be examined using theimage sensor 490.

In the embodiments described above, the image sensor 490 comprises 2sensing areas 190 and moves through 3 location groups of 2 image capturelocations. In general, the image sensor 490 may comprise N sensing areas(N is a positive integer) and move through P location groups (P is aninteger greater than 1), wherein each location group may have any numberof image capture locations. As a result, the numbers of image capturelocations of the location groups do not have to be the same.

In the embodiments described above, the image sensor 490 moves betweenthe 6 image capture locations in the order of the first, second, third,fourth, fifth, and then sixth image capture locations. In general, theimage sensor 490 may move between the 6 image capture locations (or anynumber of image capture locations) in any order. For example, the imagesensor 490 may move between the 6 image capture locations in the orderof the first, second, third, fifth, sixth, and then fourth image capturelocations.

In the embodiments described above, the object/scene 510+512 remainsstationary and the image sensor 490 moves relative to the object/scene510+512. In general, any moving arrangement may be possible as long asthe image sensor 490 moves relative to the object/scene 510+512. Forexample, the image sensor 490 may remain stationary and the object/scene510+512 may move relative to the image sensor 490.

In the embodiments described above, the partial images 520.1, 520.2, and520.3 are stitched to form the stitched image of the object/scene510+512. In general, a combination of partial images with one partialimage from each partial image group may be stitched to form a stitchedimage of the object/scene 510+512. For example, the partial images520.1, 520.5, and 520.6 may be stitched to form a stitched image of theobject/scene 510+512.

In the embodiments described above, stitching is performed then enhancedpartial images are determined and used to enhance the stitched image.Alternatively, enhanced partial images are determined before stitchingis performed. For example, the first, second, and third enhanced partialimages may be determined as described above. Then, the first, second,and third enhanced partial images may be stitched to form a combined andcomplete image of the object/scene 510+512 (e.g., image 620 of FIG. 6D).Many other possible ways of handling the 6 partial images 520.1-6 may beused to form the combined and complete image of the object/scene510+512.

In the embodiments described above, the first, second, and thirdenhanced partial images are used to replace the corresponding partialimages in the stitched image. In an alternative embodiment, an enhancedpartial image of a partial image group is not used for such replacementif the enhanced partial image does not have a higher resolution thanthat of the partial image which the enhanced partial image is supposedto replace in the stitched image.

For example, the first enhanced partial image of the first partial imagegroup is not used to replace the partial image 520.1 of the stitchedimage if the first enhanced partial image does not have a higherresolution than the resolution of the partial image 520.1. Thissituation occurs when the distance (or offset) between the correspondingfirst and fourth image capture locations is K times the size of thesensing element 150, wherein K is a non-negative integer.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

What is claimed is:
 1. A method of using an image sensor comprising Nsensing areas for capturing images of a scene, N being a positiveinteger, the N sensing areas being physically separate from each other,the method comprising: for i=1, . . . , P, and j=1, . . . , Q(i),positioning the image sensor at a location (i,j) relative to the sceneand capturing a partial image (i,j) of the scene using the image sensorwhile the image sensor is at the location (i,j), thereby capturing intotal R partial images, wherein R is the sum of Q(i), i=1, . . . , P,wherein P is an integer greater than 1, wherein Q(i), i=1, . . . , P arepositive integers and are not all 1, wherein for i=1, . . . , P, alocation group (i) comprises the locations (i,j), j=1, . . . , Q(i), andwherein a minimum distance between a location of a location group of thelocation groups (i), i=1, . . . , P and another location of anotherlocation group of the location groups (i), i=1, . . . , P issubstantially larger than a maximum distance between two locations of alocation group of the location groups (i), i=1, . . . , P; anddetermining a combined image of the scene based on the R partial images.2. The method of claim 1, wherein N is greater than
 1. 3. The method ofclaim 1, wherein said positioning the image sensor at the locations(i,j) for i=1, . . . , P, and j=1, . . . , Q(i) are performed one byone.
 4. The method of claim 1, wherein Q(i), i=1, . . . , P are the sameand greater than
 1. 5. The method of claim 1, wherein said minimumdistance is close to and less than a size of a sensing area of the Nsensing areas.
 6. The method of claim 1, wherein said minimum distanceis more than 100 times said maximum distance.
 7. The method of claim 1,wherein said maximum distance is less than 10 times a size of a sensingelement of the N sensing areas.
 8. The method of claim 1, wherein saidpositioning the image sensor at the locations (i,j) for i=1, . . . , P,and j=1, . . . , Q(i) comprises moving the image sensor from a locationof a location group of the location groups (i), i=1, . . . , P directlyto another location of another location group of the location groups(i), i=1, . . . , P and does not comprise moving the image sensor from alocation of a location group of the location groups (i), i=1, . . . , Pdirectly to another location of the same location group.
 9. The methodof claim 1, wherein said determining the combined image comprisesstitching the partial images (i,1), i=1, . . . , P to form a stitchedimage of the scene.
 10. The method of claim 9, wherein said determiningthe combined image further comprises for i=1, . . . , P determining anenhanced partial image (i) based on the partial images (i,j), i=1, . . ., Q(i).
 11. The method of claim 10, wherein said determining thecombined image further comprises for i=1, . . . , P using the enhancedpartial image (i) to replace the partial image (i,1) of the stitchedimage.
 12. The method of claim 11, wherein said determining the combinedimage further comprises equalizing resolutions of different regions ofthe stitched image after said using is performed.
 13. The method ofclaim 10, wherein said determining the combined image further comprisesfor i=1, . . . , P using the enhanced partial image (i) to replace thepartial image (i,1) of the stitched image if a resolution of theenhanced partial image (i) is higher than that of the partial image(i,1).
 14. The method of claim 13, wherein said determining the combinedimage further comprises equalizing resolutions of different regions ofthe stitched image after said using is performed.
 15. The method ofclaim 10, wherein said determining the enhanced partial images (i)comprises determining positions of the locations (i,j), j=1, . . . ,Q(i) relative to each other.
 16. The method of claim 15, wherein saiddetermining the positions of the locations (i,j), j=1, . . . , Q(i)relative to each other comprises using markers which are stationaryrelative to the scene.
 17. The method of claim 15, wherein saiddetermining the positions of the locations (i,j), j=1, . . . , Q(i)relative to each other comprises: upsampling the partial images (i,j),j=1, . . . , Q(i) resulting in upsampled partial images (i,j), j=1, . .. , Q(i) respectively; and correlating the upsampled partial images(i,j), j=1, . . . , Q(i) to determine the positions of the locations(i,j), j=1, . . . , Q(i) relative to each other.
 18. The method of claim1, wherein said determining the combined image comprises for i=1, . . ., P determining an enhanced partial image (i) based on the partialimages (i,j), j=1, . . . , Q(i).
 19. The method of claim 18, whereinsaid determining the combined image further comprises stitching theenhanced partial images (i), i=1, . . . , P to form a stitched image ofthe scene.
 20. The method of claim 19, wherein said determining thecombined image further comprises equalizing resolutions of differentregions of the stitched image.
 21. The method of claim 18, wherein saiddetermining the enhanced partial images (i) comprises determiningpositions of the locations (i,j), j=1, . . . , Q(i) relative to eachother.
 22. The method of claim 21, wherein said determining thepositions of the locations (i,j), j=1, . . . , Q(i) relative to eachother comprises using markers which are stationary relative to thescene.
 23. The method of claim 21, wherein said determining thepositions of the locations (i,j), j=1, . . . , Q(i) relative to eachother comprises: upsampling the partial images (i,j), j=1, . . . , Q(i)resulting in upsampled partial images (i,j), j=1, . . . , Q(i)respectively; and correlating the upsampled partial images (i,j), j=1, .. . , Q(i) to determine the positions of the locations (i,j), j=1, . . ., Q(i) relative to each other.